A toggle-type mold clamping device for clamping a mold provided in an injection molding machine in general has a function of connecting a movable platen supporting a movable mold and a cross head moving forward and backward by a driving portion supported by a pressure receiving platen by a toggle link mechanism and of increasing a pressurizing force of the cross head and transmitting it to the movable platen, and a predetermined mold clamping force is generated based on expansion of a tie bar in a state in which the toggle link mechanism has been expanded substantially to the full. Therefore, it is necessary to set a position of the pressure receiving platen so that a predetermined mold clamping force is generated, and the position of the pressure receiving platen is automatically set in usual by a mold thickness adjusting device.
As a prior-art method of adjusting a mold thickness using this type of mold thickness adjusting devices, a method of adjusting a mold thickness in an injection molding machine already proposed by the applicant and disclosed in Patent Document 1 is known. This method of adjusting a mold thickness includes, in mold thickness adjustment by moving the pressure receiving platen to a predetermined position, a first process in which in a state in which the toggle link mechanism is expanded, the pressure receiving platen is moved forward from a retreated position at a first speed, which is a high speed, and when the pressure receiving platen has reached a mold closure position, the platen is moved backward only by a predetermined distance, a second process in which after the first process, the pressure receiving platen is moved forward at a second speed, which is a low speed, and when the pressure receiving platen has reached the mold closure position, the toggle link mechanism is bent and the mold is opened only by a predetermined distance and after that, the pressure receiving platen is moved forward only by a distance corresponding to a clamping margin to obtain a targeted clamping force, and a third process in which after the second process, the pressure receiving platen is moved backward only by a predetermined distance (correction distance) so as to make correction, and the method had advantages that the number of work processes can be reduced, production efficiency can be improved, and sufficient accuracy and stability can be ensured.